Demonstrate
Definition
Show how something works or is true, using evidence, examples or steps.
Explanation
In mathematics it often means to show the working. In other subjects it may mean to give evidence that something is true.
Example
Demonstrate that the sum of two even numbers is even.
In an exam
Command-word meanings can vary between subjects, exam boards and mark schemes, so check your own board's guidance. See Exam Command Words: What Each Instruction Asks For.
Common confusion
The meaning varies by subject. Check your exam board guidance.